A known problem to be solved in conjunction with such a process is to prevent, correct or reduce misalignments between the printed pattern and the embossed pattern.
To solve this problem, EP 2636524 A1 suggests to preheat the substrate carrying the printed pattern and to stretch it thereafter in a controlled manner, so as to adjust the pitch of the printed pattern to the pitch of the embossed pattern. However, it is well known in the art that a longitudinal stretching causes a transversal necking of the flexible substrate, thereby transversely deforming the printed pattern. To avoid such an undesired transversal necking of the substrate, EP 2636524 A1 suggests that the stretching of the substrate carrying the printed pattern shall take place in several pairs of heated, small diameter cylinders, which are located upstream of a bigger diameter embossing cylinder. It will consequently be appreciated that the stretching as proposed in EP 2636524 A1, necessitates considerable stretching equipment in the production line. Furthermore, to carry out the proposed process, the substrate carrying the printed pattern must be easily stretchable without any major drawbacks, which is surely not the case for every otherwise desirable substrate. To be less limited in the choice of the substrate, EP 2636524 A1 further suggests to print the printed pattern onto an auxiliary film, and to stretch this film it in a controlled manner, so as to continuously adjust the pitch of the printed pattern on the auxiliary film to the pitch of the embossed pattern, before laminating the stretched film onto the moving substrate. However, this way to proceed makes the proposed process even more complicated.
Hence, there is a need for a simpler process for preventing or reducing misalignments between the printed pattern and the embossed pattern.